Intentionally or not, the Republican vice presidential nominee was on to something. After a brief exchange, Gibson explained that he was referring to the idea -- enshrined in a September 2002 White House strategy document -- that the United States may act militarily to counter a perceived threat emerging in another country. But that is just one version of a purported Bush doctrine advanced over the past eight years.

Peter D. Feaver, who worked on the Bush national security strategy as a staff member on the National Security Council, said he has counted as many as seven distinct Bush doctrines. They include the president's second-term "freedom agenda"; the notion that states that harbor terrorists should be treated no differently than terrorists themselves; the willingness to use a "coalition of the willing" if the United Nations does not address threats; and the one Gibson was talking about -- the doctrine of preemptive war.

"If you were given a quiz, you might guess that one, because it's one that many people associate with the Bush doctrine," said Feaver, now a Duke University professor. "But in fact it's not the only one."

This debate may ordinarily be little more than cocktail chatter for the foreign policy establishment, but political blogs were buzzing yesterday over Palin's entire interview with Gibson, including the confusion about the doctrine. Liberals said it was yet another case of Palin's thin grasp on foreign policy, while conservatives replied that she handled herself well by putting the question back on Gibson.

After she asked Gibson to clarify what he meant, the anchor pressed Palin on whether the United States has "a right to make a preemptive strike against another country if we feel that country might strike us."

"Charlie," Palin replied, "if there is legitimate and enough intelligence that tells us that a strike is imminent against American people, we have every right to defend our country. In fact, the president has the obligation, the duty to defend."

The campaign of Democratic Sen. Barack Obama directed reporters to online commentary about the exchange. "What Sarah Palin revealed is that she has not been interested enough in world affairs to become minimally conversant with the issues," journalist James Fallows wrote on TheAtlantic.com. "Many people in our great land might have difficulty defining the 'Bush Doctrine' exactly. But not to recognize the name, as obviously was the case for Palin, indicates not a failure of last-minute cramming but a lack of attention to any foreign-policy discussion whatsoever in the last seven years."

Conservatives ridiculed such reasoning. "What a bunch of nonsense," Andrew C. McCarthy wrote on National Review Online. "Peanut gallery denizens like me, who don't have states to run and who follow this stuff very closely, disagree intensely among ourselves about what the Bush Doctrine is."

Outside foreign policy experts offered different reads on the question. Richard C. Holbrooke, who served key posts in both the Clinton and Carter administrations, said he saw the 2002 National Security Strategy of the White House as the critical statement of a Bush doctrine. (The White House staff member who helped draft the 2002 document, Stephen E. Biegun, now serves as Palin's foreign policy adviser.)

The strategy document itself articulates the principle as follows: "The greater the threat, the greater is the risk of inaction -- and the more compelling the case for taking anticipatory action to defend ourselves, even if uncertainty remains as to the time and place of the enemy's attack. To forestall or prevent such hostile acts by our adversaries, the United States will, if necessary, act preemptively."